U.S. Democratic presidential candidate Barack Obama has met with U.S. military commanders in Afghanistan, at the start of an international tour designed to boost his foreign policy credentials.

Obama visited Bagram air force base in eastern Afghanistan Saturday as part of a congressional delegation that includes two other U.S. senators.  The U.S. military says commanders briefed the lawmakers about the war effort.

Afghan officials say Obama will meet with President Hamid Karzai during his visit.

He is also expected to travel to Iraq.

Before his trip, Obama told reporters he wanted to talk with commanders in both major war zones to get a sense of their concerns.

Obama has suggested withdrawing troops from Iraq and increasing the military presence in Afghanistan, which he says is more important in the fight against terrorism.

In a radio address today, Republican candidate John McCain criticized Obama for announcing a war strategy before his trip.

Senator McCain said that apparently Obama is confident he will not learn anything during his tour that might change his position.

Iraqi Prime Minister Nouri al-Maliki is quoted in a German news weekly as saying he supports Obama's Iraq policy.  He says the senator's plan to withdraw troops within 16 months would be about the right timeframe.

Mr. Maliki made clear that he is not endorsing any candidate for the U.S. presidency.

Obama's international tour will also include stops in Israel, Jordan, Germany, France and Britain.

Palestinian officials say he will meet with leaders in the West Bank next week.  

Some critics have said Obama, a first term senator, is too inexperienced in international affairs to serve as commander in chief.

Some information for this report was provided by AFP, AP and Reuters.